The present invention relates to devices and methods for use in stereotactic surgery, providing devices and methods for holding a probe in place during and after stereotactic surgery. More particularly, the invention provides a device and a method for maintaining the position of a probe, such as an electrode, a deep brain stimulator, a cryoprobe, a cannula, or the like, following stereotactic placement of the probe in a patient""s body.
Stereotactic techniques enable surgeons and researchers to direct surgical instruments with great accuracy to targets within the central nervous system, particularly the brain, brainstem, and spinal cord of a patient. Stereotactic surgery is typically carried out using a stereotactic frame and associated adapters and devices, which enable the surgeon to guide surgical instruments to identified targets within the brain, spinal cord, or other part of the central nervous system. Stereotactic frames are typically ring-shaped structures mounted to the head of a patient to provide a fixed reference with respect to the patient""s brain, and may be used to determine a three-dimensional data set for accurately locating the target site or anatomical structure of interest during a surgical or diagnostic procedure.
A stereotactic frame may comprise two or more parts. For example, the head-mounted frame may fit into another large frame, which may be used to position a probe to be introduced into the patient and to provide support for a drive mechanism used to maneuver a probe to its target position. Typically, a stereotactic frame has a rail, often in the shape of an arc, that extends above and across the patient""s skull. A rail-mounted guide can be positioned at any suitable location along the length of the rail to serve as a guide for surgical instruments and drive mechanisms. Commonly used stereotactic frames include the Leksell, the Riechert-Mundinger, the Todd-Wells, and the Brown-Roberts-Wells devices. Examples of stereotactic frames and devices may be found in U.S. Pat. Nos. 5,649,936 and 5,817,106 to Real; U.S. Pat. No. 5,643,286 to Warner et al.; and U.S. Pat. No. 5,618,288 to Calvo. A removable guide mounting to a burr-hole in the skull is disclosed in U.S. Pat. No. 4,998,938 to Ghajar et al.
Stereotactic techniques are used in investigative and experimental surgeries, as well as surgeries performed for diagnostic, prophylactic, or therapeutic purposes. Stereotactic frames are commonly used when performing placement of deep brain stimulators, brain biopsies, tumor removal, and other modalities of deep brain surgery where the surgeon requires guidance to properly position an instrument. In performing these surgeries, a variety of surgical, diagnostic, and observational instruments may be used with stereotactic devices including electrodes, cannulae, catheters, biopsy instruments, stimulators, ablators, heating elements, cryosurgical probes, and the like. Such instruments may be used to affect, alter, or excise tissue, or to place drugs, cells, tissues or devices at a specific location in the brain and central nervous system. Stereotactic surgical techniques are used, for example, in the placement of deep brain stimulators, where ongoing stimulation of specific locations within the brains of patients is used to relieve symptoms of Parkinson""s disease and other neurological disorders. Stereotactic techniques are also used for the placement and positioning of catheters, cannulae, and other devices for sampling or for delivery (by microinjection, microdialysis, or other means) of drugs or other therapeutic, diagnostic or experimental agents, cells or tissues, for biopsies, for lesioning, for resection, and the like.
For example, stereotactic techniques using stereotactic frames are useful for microelectrode guidance. Stereotactic microelectrode guidance is used in the treatment of Parkinson""s disease, epilepsy, and other neurological conditions, for the placement and positioning of electrodes, such as deep brain stimulators, for localization of brain nuclei and brain mapping, and other probes for neuronal stimulation, neuronal recording, and ablation of precise locations within the brain of a patient.
Any instrument introduced into the brain of a patient may be termed a xe2x80x9cprobe.xe2x80x9d Thus, a probe may be a deep brain stimulator, a recording electrode, a cannula, a catheter, an ablator, or other instrument. Probes are typically introduced into the patient""s brain through a burr hole in the skull. An important use of stereotactic surgical techniques is for the placement of probes into the brain or other organs, where the probes are intended to remain in place for extended periods of time, or even permanently. The final positioning of a probe in a stereotactic procedure is typically accomplished using a microdrive, which provides greater precision of motion than other, more coarse drive mechanisms.
In order to achieve successful long-term or permanent implantation, the probe is commonly attached securely to a solid structure on the patient, such as the skull, to anchor it in its proper position. Typically, a glue or cement is applied to the portion of the probe adjacent the burr hole, although other methods of securely attaching the probe may also be used, such as sutures, or plates, rings or caps adapted to hold the probe and cover the burr hole. Thus, in order not to lose its precise placement in the brain, brainstem, or spinal cord of the patient, the probe must accurately maintain its position during the anchoring procedure, such as during the setting of the glue or cement. However, attempting to hold the probe at a point at or above the arc of the stereotactic frame allows for movement of the probe within the brain of the patient. In addition, the stereotactic apparatus is typically partially disassembled to expedite the anchoring procedure. Such disassembly can introduce mechanical displacement, disturbing the probe and moving it from its desired location. Incorrect placement of a probe reduces the degree of, or entirely prevents, the success of the surgical procedure. Accordingly, there is a need in the art for devices and methods that maintain the correct position of the probe during anchoring of the probe in the patient and during partial disassembly of the stereotactic apparatus.
The invention is addressed to the aforementioned need in the art, and provides novel devices and methods for holding a probe, such as a deep brain stimulator, following stereotactic placement of the probe in a desired location in a patient""s body, thus providing stability and maintenance of probe placement during potentially disruptive post-placement activities such as removal of a microdrive. The invention provides means to hold a probe in position, following positioning by stereotactic procedures, while means for more permanent immobilization are affixed to the probe for long-term implantation in a patient""s brain.
Accordingly, it is an object of the invention to provide a stereotactic probe holder for maintaining a probe in position, where the stereotactic probe holder contacts the probe at a position between a stereotactic frame and a patient""s head, and where the stereotactic probe holder comprises an adjustable support, a locking means effective to substantially immobilize the stereotactic probe holder, and a gripping means, attached to the adjustable support, that is effective to hold the probe.
It is another object of the invention to provide a stereotactic probe holder for holding a probe in position, where the stereotactic probe holder contacts the probe at a position between a stereotactic frame and a patient""s head, where the adjustable support of the stereotactic probe holder comprises a rotation means capable of rotation around an axis, and a radial positioning means attached to the rotation means that can slide inwardly and outwardly with respect to the rotation means. The stereotactic probe holder further comprises gripping means attached to an end of the radial positioning means, whereby adjustment of the radial positioning means allows movement of the gripping means in a plane substantially orthogonal to the axis of the rotation means.
It is a further object of the invention to provide a method for holding a probe following placement of the probe using a stereotactic apparatus, comprising the steps of providing a stereotactic probe holder that includes a gripper and a locking means, affixing the gripper onto the probe, and applying the locking means to substantially immobilize the stereotactic probe holder so as to maintain the probe in position.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
In one aspect, then, the present invention relates to a stereotactic probe holder for maintaining a probe in position following positioning of the probe in a patient""s brain, brainstem or spinal cord by stereotactic procedures. The stereotactic probe holder includes a gripper attached to an adjustable support, where the position of the gripper may be adjusted so as to contact a probe at a position between a stereotactic frame and a patient""s head. The stereotactic probe holder also includes a locking means capable of substantially immobilizing the stereotactic probe holder so as to hold the probe in position.
In another aspect, the invention relates to the above stereotactic probe holder, wherein the adjustable support comprises a rotation arm capable of rotation around an axis, and a shaft attached to the rotation arm that can slide inwardly and outwardly with respect to the rotation arm. In this aspect, the gripper is attached to the shaft. Adjustment of the rotation arm is effective to maneuver the gripper about the axis. That is, rotating the rotation arm maneuvers the gripper angularly around the axis, while longitudinal adjustment of the rotation arm makes possible displacement of the gripper in a direction parallel to the axis. Adjustment of the shaft is effective to maneuver the gripper in a plane substantially orthogonal to the axis of the rotation arm, by adjusting the length of the radius separating the gripper from the rotation arm.
In another aspect, the invention provides a method for holding a probe following stereotactic probe placement during surgery using stereotactic apparatus, comprising the steps of providing a stereotactic probe holder that includes a gripper and a locking means, affixing the gripper onto the probe in a position between the stereotactic frame and the patient""s head, and applying the locking means to substantially immobilize the stereotactic probe holder so as to maintain the probe in position.